A local area network (LAN) is a number of computers connected to each other in a single location, usually a single floor of a building or all the computers in a small company.

Benefits of LAN:

1. Allow more efficient management of resources.
2. Help keep information reliable and up-to-date.
3. Help speed up data sharing.
4. Allow workgroups to communicate more.
5. Help business service their clients more efficiently.

There three roles for computers in a LAN:

1. Clients, which use but do not provide network resources.
2. Peers, which both use and provide network resources.
3. Server, which provide network resources

The type of operating system a computer uses determines each of these computer roles. Server run network operating systems such as Window 2000, Window 2003 or Window 2008. Clients run client operating systems, such as Window XP, Window Vista or Micintosh operating system.

Based on the roles of the computers attached to the network, networks are divided into three types:

Server-based (also called client-server): Contains clients and the servers that support them.

Peer-to-peer: Has no servers and uses the network to share resources among independent peers.

Hybrid network: Is a cleint-server network that also has peers sharing resources. Most networks are actually hybrid networks.